Abstract:

Taking the electromagnetic system of an AC contactor as an example,the mechanism and key influencing factors of noise generation in AC electromagnets are theoretically investigated.Through Ansys finite element electromagnetic simulation,it is concluded that five parameters—the inner pole area of the short-circuit ring,contacting airgap between the core pole surfaces,coil power angular frequency,short-circuit ring resistance,and short-circuit ring turns are critical factors affecting electromagnetic noise suppression.These parameters can be optimized using three equations:the pole area ratio between inner and outer of the short-circuit ring,the phase difference of magnetic fluxes between inner and outer of the short-circuit ring, and the comprehensive coefficient of the short-circuit ring.A categorical analysis of contactor electromagnetic system noise is conducted to identify the corresponding root causes.Finally,several simulation examples validate the correctness of the conclusions.

Key words: AC electromagnet, electromagnetic noise, noise suppression, contact airgap, magnetic divide effect, noise with short-circuit ring